Access doors are sometimes provided in the aircraft skins to allow service personnel access to various internal systems. For example, access doors may be provided on the underside of aircraft wings in order to permit access to internal wing fuel tanks. Some of these access doors must be designed to withstand impact loads from debris while retaining a fluid tight seal to prevent the escape of fuel following an impact. In the case of aircraft wing skins formed of metal, these access doors may also be made of metal and may require high impact resistance.
The use of composite skins in some newer aircraft present challenges in designing suitable access doors, particularly for wing mounted fuel tanks. Metal access doors can add undesirable weight to the aircraft and may present material incompatibilities when used with certain composite skins, such as carbon fiber reinforced plastic (CFRP) laminates. Other design challenges include the need to meet requirements for electrostatic performance, lightning strike and impact resistance. In addition, the access doors must include fuel tight seals that prevent fuel leakage over the aircraft's expected service life.
Accordingly, there is a need for an access door for composite aircraft structures such as CFRP laminate wing skins which is lightweight, line replaceable and meets a variety of performance specifications required by aircraft regulating authorities.